Scrambler troubleshooting

Started by chokeyou, September 18, 2004, 09:01:14 PM

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chokeyou

//www.goodbyebeautiful.com/pedal/scrambler.mp3

thats about the extent of the distortion i can get out of it, texture is entirely counter clockwise and so is blend...this cant be right, anybody have any ideas what my problem could be?

Fret Wire

Are you still getting the same tranny voltages as the last time? Did you look over the whole board with a magnifying glass to check for other solder problems?
Fret Wire
(Keyser Soze)

chokeyou

yes, same voltages give or take a few hundreths of a volt. I havent gone over it with a magnifying glass, but i have with my multimeter and the continuity checker. as far as i can tell, everything is soldered together right and well. the one thing that actually worries me is the collector of Q2, it still seems low (3.03 instead of 4.6), and since i have a 9.13 volt supply and all my values are higher than the values found at http://www.generalguitargadgets.com/instructions/scrambler_inst.htm im pretty sure that i'm having a problem with Q2. i still cant read these layouts and schematics for crap...what does my problem mean?

Lonestarjohnny

Choke, your doin great, just a silly lil mistake like that trace is all it take's sometime's to get me pullin my hair out, but your doin a good job, I use a Dentest plac removeing tool and go around and clean the Flux and loose solder from around all trace's to just make sure there are no bridge's for me to loose signal on,
keep on, you'll get it.
The voltages are close now on your trannys,, you should get good signal, and if sounds good go with.
Johnny

chokeyou

well i'm getting signal and a slight amount of distortion, the blend pot is basically useless its either none or all and texture pot does very very little from what i can hear....this isnt the pedal i originally wanted to build! whats wrong with this dumb thing...possibly log pots? agh its just confusing...i've gone through and etched between everything and no change in sound...bleh

now Q2's collector is 2.59...its going the wrong direction...help!

I also remeasured the resistance between the 1 & 3 lugs of the 50K pot...only to find out it measures about 30K....this pot seems to be all over the place and crap...i took it apart and cleaned it up some, no luck...stupid little pots...and of course i've drilled my enclosure for them already...no way i could fit a big pot in there. should i just order another one from small bear and make him check that it works first? (it used to be 60K etc...really all over the place)

Fret Wire

Which transistors are you using? There are a lot of variations with the pinouts of the 2N5306.
Fret Wire
(Keyser Soze)

chokeyou

i'm using 2n5306 and one bc169b

Jason Stout

I would double check the connections on both sides of R5 R6 and C4 to make sure that they are only connected where they need to be. Check R4 and C6 as well.
About measuring pots/resistors, in most cases you will need to measure them while they are physically out of the circuit, otherwise you may be measuring some sum of parallel resistances, which will be less than the resistor alone.
About circuit board rework - be careful, I have ruined my fair share of boards from multiple soldering/de-soldering eventually the traces will lift. Invest in some solder wick (Radioshack in U.S.) it works wonders for cleaning problem areas.
Jason Stout

sovtek50

Well, I had the same problem. Until my wife went out and bought...
No, what You gotta do is, check for the correct wiring of the Blend pot. You used the Tonepad layout, right? It can be mixed up easily. Make sure the wiper of said pot goes to output. That should do it. Did it for me. Suddenly there's lotsa gain, and the Texture pot starts to work.
A circuit a day keeps the therapist away.